The development of a diabetes-like syndrome in mice by the M- variant of encephalomyocarditis (EMC) virus seems to depend on the function of beta cells as well as alpha cells. Thus, the correlation between EMC-virus multiplication and beta cell degranulation and degeneration is being studied in vitro and in vivo. Further, the relationship between the release of insulin and multiplication of virus in the pancreatic beta cell will be studied in vitro. In addition, genetic factors that may play a role in the development of diabetes is being studied in the mice of F1 and F2 generation.